1. Field of the Invention
The present invention relates to an air bag module mounting structure for mounting an air bag module on a steering wheel of a vehicle or the like.
The present application is based on Japanese Patent Applications No. 2000-193461, 2000-196553, 2000-198184, 2001-21280 and 2001-23088, which are incorporated herein by reference.
2. Description of the Related Art
An air bag mounting structure disclosed, for example, in JP 10-500922 is known as an air bag mounting structure of this kind. Namely, in the disclosed conventional structure, a plurality of (for example, four) pins are provided on the bottom of an air bag module in such a manner as to protrude therefrom and hook portions are formed on distal ends of the plurality of pins. A plurality of (for example, two) holding members are mounted on a core of a steering wheel and a plurality of (For example, two) passage holes are formed in the plurality of holding members in such a manner as to confront the pins. A resilient Locking wire is mounted on each of the holding members and the locking wires so mounted are disposed in such a manner as to partially extend over the respective passage holes in a direction in which the locking wires intersect with the axes of the passage holes. In addition, working holes are formed in a back cover of the steering wheel, which working holes are adapted to confront four locking locations where the hook portions and the locking wires are locked to each other.
Then, in a case where the air bag module is mounted on the steering wheel, the plurality of pins are allowed to pass through the passage holes so that the hook portions on the respective pins are brought into engagement with the locking wires in the passage holes, whereby the air bag module is locked and held onto the steering wheel in a locked fashion.
On the contrary, in a case where the air bag module is removed from the steering wheel, a removing tool such as a screw driver is inserted into the respective locking locations from the working holes so as to release the locking wires from the engagement with the hook portions sequentially against the resiliency of the locking wires. In this state, the air bag module is separated away from the steering wheel in such a manner that the pins on the air bag module are drawn out of the passage holes in the holding members so that the air bag module is removed from the steering wheel.
In the aforementioned conventional air bag module mounting structure, however, for example, in a case where the air bag module needs to be replaced after it has been mounted once, there has occurred a problem that the air bag module so mounted is difficult to be removed from the steering wheel.
Namely, with a steering wheel of a four-spoke type, working holes are formed in a back cover of the steering wheel in such a manner as to confront four locking locations where the hook portions and the locking wires are locked to each other. In this construction, in order to remove the air bag module from the steering wheel, a removing tool such as a screw driver is inserted into each of the mounting locations from the working hole so that the locking wires are deformed against their resiliency to thereby be released from the engagement with the hook portions. Thus, the engagement between the hook portions and the locking wires at the plurality of locking locations needs to be released sequentially using the screw drivers or the like, and therefore the removing work tends to become extremely troublesome and a long working time is needed.
Further, the air bag module is required to be separated from the steering wheel in a state in which the engagement between the hook portions and the locking wires is released with the removing tools at the plurality of locking locations. In this removing construction, in the event that the removing tool is dislocated from the locking location for some reason, the resilient deformation of the locking wires is released, whereby there may be caused a risk that the locking wires are abruptly returned to the lock positions thereof. Here, the steering wheel is mounted in an inclined fashion with a side of the steering wheel where the air bag module is mounted being oriented upwardly relative to the steering shaft. This has led to a problem that the pin or pins which are released from the engagement with the locking wires are caused to fall in the passage holes again by virtue of the gravity of the steering wheel for re-engagement with the locking wires.
Moreover, with the steering wheel being mounted on the steering shaft, air bag module removing work needs to be carried out from the back side of the steering wheel or within a narrow space formed between the steering wheel and the instrument panel. This makes extremely troublesome the insertion of the removing tools into the locking locations in trying to release the engagement between the hook portions and the locking wires, and moreover, the inserted removing tools have tended to be easily dislocate, requiring a long working time for removal of the air bag module.
Further, a steering wheel with an air bag device disclosed, for example, in JP 11-59304 is also known as a steering wheel with an air bag device of this type.
Namely, as shown in FIG. 29, the conventional steering wheel 100 comprises an air bag module 110 adapted to oscillate relative to a core 101 thereof and a plurality of horn switch mechanisms 130. A hole 103 is formed in each spoke portion 102 of the core 101 of the steering wheel 100, and locking members 111 are provided on a bottom of the air bag module 110 which are adapted to engage with the holes 103, respectively, in such a manner as to oscillate relative to the holes 103. The locking member comprises a base portion 112a and a plurality of locking pawls 113 forming as a whole a cylindrical shape adapted to be contracted diametrically. A through hole 112a is formed in the base portion 112 at a central portion thereof, and an annular breakable groove is formed in the outer circumference of the base portion 112. On the other hand, a taper portion 113a is formed at an inner circumferential distal portion of the locking pawls 113 which is formed such that the inner circumference thereof expands diametrically toward the distal end thereof. The locking member 111 is screwed to the core with a pin 120 having a threaded portion 121 which is allowed to pass through the through hole 112a and a mounting hole 110a in the air bag module 110 and a nut 123 screwed on the threaded portion 121. Provided at an opposite end to the threaded portion 121 of the pin 120 is a head portion 122 which is spaced away from the locking pawls 113 and which has an outer circumferential surface tapered so as to conform to the taper portion 113a of the locking pawls 113. In addition, springs 125 are provided between the air bag module 110 and the spoke portions 102 for biasing the air bag module 110 and the spoke portion 102 in directions in which they are separated away from each other.
In the air bag module 110 disposed as described above, when a cover 110b disposed at an upper portion thereof is pressed in a direction toward the core 101 (in a direction indicated by an arrow A in FIG. 29) against the biasing force exerted by the springs 125, the locking members 111 and the pins 120 are also displaced in the same direction. On the contrary, when the force pressing down the cover 110b is removed the locking members 111 and the pins 120 are displaced by the biasing force of the springs 125 in an opposite direction to the direction in which they are pressed down to a position where the locking pawls 113 are brought into engagement with circumferential edge portions of the holes 103 in the spoke portions 102.
In addition, the horn switch mechanisms 130 are provided in the vicinity of the locking members 111, respectively, between the air bag module 110 and the spoke portions 102. The horn switch mechanism 130 comprises contacts 131 mounted on the air bag modules 110 and contacts 132 mounted on the spoke portions 120 in such a manner as to be spaced away from the contacts 131, respectively. These contacts 131, 132 are brought into contact with each other when the cover 110b is pressed down in the direction A and the air bag module 110 is displaced, and on the contrary, when the pressing force is removed and the air bag module 110 is displaced in the opposite direction to the direction A, the contacts are separated away from each other. Thus, in this steering wheel 100, the air bag module 110 also functions as part of the horn switch, and the steering wheel 100 is constructed as a steering wheel of a so-called floating type.
Incidentally, when an impact which is greater than a predetermined magnitude is applied to a vehicle equipped with the steering wheel 100 an air bag 110c installed in the interior of the air bag module 110 is deployed. As this occurs, a force of an extremely large magnitude is exerted on a bottom portion of the air bag module in a direction in which the air bag module 110 is separated away from the core 101.
In the steering wheel 100, in the event that the force of such a great magnitude is applied thereto, the locking members 111 are adapted to be broken at the breakable grooves 114 in the base portion 112 before the engagement between the locking pawls 113 on the locking members 111 and the holes 103 in the spoke portions 120 is released. Then, with this breakage at the grooves, the air bag module 110 is displaced in the opposite direction to the direction A together with the base portions 112 of the locking members 111 and the pins 120, and the head portions 122 of the pins 120 are brought into contact with the taper portion 113a of the locking pawls 113. The contact of the head portions 122 with the locking pawls 113 regulates the displacement of the air bag module 110 in the opposite direction to the direction A.
Incidentally, the conventional structure as described above has caused the following problems.
Namely, the horn switch mechanisms 130 are constructed not to operate before the air bag module constituted by a number of components is assembled to the core 101. In a case where the control of the stroke of the horn switch mechanism 130 is tried to be implemented in this construction, the required control has to be carried out after the air bag module 110 has been assembled to the core 101, and in the event that there are caused errors in production and assembly of the components, it is difficult to set a predetermined stroke by correcting those errors.
In addition, in the locking member 111, the supporting strength with which the locking member 111 is locked into the core 101 and the breaking strength at which the locking member 111 breaks at the breakable groove 114 needs to be set with finely controlled balance and good accuracy. That is, with the supporting strength being set too high, the rigidity of the locking member 111 is increased, and when an assembling person tries to assemble the components, there may be caused a problem that the locking member 111 is difficult to be fitted in the hole 103. In contrast to this, with the supporting strength being set too low, at the time of operation of the air bag module 110, there may be caused a risk that the engagement between the locking pawls 113 and the circumferential edge portions of the holes 103 is released before the locking members 111 break at the breakable grooves 114, thereby causing in turn a risk that the holding of the air bag module 110 becomes unstable.
Additionally, the core 101 is normally formed by casting. Due to this, the resin hole 103 into which the locking member 111 is inserted in such a manner as to oscillate relative to the hole needs to be worked so accurately that there is left no burr on an inner circumferential surface thereof in order to secure the smooth oscillation of the locking member 111 relative to the hole 103. This serves to increase the production cost.
Furthermore, in this conventional construction, since the pin 120 itself oscillates, the supporting rigidity of the air bag module 110 tends to become unstable. To cope with this, for example, a counter measures is taken to prevent the generation of a risk of the horn being activated against the driver""s intention by the unbalanced sinking (so-called rolling) of the air bag module 110 during a sudden turning of the vehicle by increasing the load of the springs 125. The increase in load of the spring 125 makes the driver feel that the weight of the air bag module 110 is heavy to operate when he or she tries to operate the horn, thus deteriorating the operation feeling of the horn.
The invention was made in view of the problems inherent in the conventional air bag module mounting structure, and an object thereof is to provide an air bag module mounting structure for facilitating the removal of an air bag module from a steering wheel.
With a view to attaining the object, according to a first aspect of the invention, there is provided an air bag module mounting structure in which an air bag module is mounted on a steering wheel by allowing a plurality of pins provided on a bottom of the air bag module in such a manner as to protrude therefrom to pass through a plurality of passage holes formed in a steering wheel and bringing a hook portion formed in each of the plurality of pins into engagement with a locking body provided in the plurality of passage holes, the air bag module mounting structure being characterized by provision of a changeover member for changing over the status of the locking body between a lockable status where the air bag module is allowed to be locked onto the steering wheel and a removable status where the air bag module is allowed to be removed from the steering wheel for disposition of the locking body in each of the statuses.
Thus, according to the first aspect of the invention, by changing over the status of the locking body to the removable status for disposition of the locking body in that status the removal of the air bag module can be facilitated while preventing the abrupt return of the locking body to the lockable status.
In the first aspect of the invention, the change over member may be adapted to hold the locking body in the removable status when the air bag module is removed from the steering wheel.
Thus, since the locking body is held in the removable status when the air bag module is removed, the removal of the air bag module can be implemented quickly and more easily.
In the above air bag module, the changeover member may include return means for returning the locking body disposed in the removable status to the lockable status.
Thus, the locking body can be easily returned to the lockable status by operating the return means after the removal of the air bag module has been completed, whereby when the air bag module is mounted again on the steering wheel the required mounting work can be carried out quickly and easily.
Further, the locking body may be constituted by a single continuous wire formed into substantially a ring-like shape.
Thus, the number of parts can be reduced, and when removing the air bag module, the status of the single locking body only has to be changed over to the removal status for disposition thereof in that status, whereby the removal of the air bag module can be implemented more quickly and easily.
Still further, when disposed in the removable status the locking body may be adapted to be released from the engagement with the plurality of hook portions at one time.
Thus, the engagement between the hook portions and the locking body at the plurality of locations can be released at one time by changing over the locking body to the removable status for disposition thereof in that status.
Still further, the return means is adapted to return the locking means from the removable status to the lockable status by making use of its own resiliency.
Thus, the locking body can be automatically returned to the lockable status by its own resiliency by operating the return means, whereby when the air bag module is mounted again on the steering wheel the required mounting work can be carried out more quickly and easily.
Still further, at least part of the changeover member may be also adapted to function as an operating portion for moving the locking body from a lock position where the locking body is brought into engagement with the plurality of pins to a release position where the locking body is released from the engagement with the plurality of pins.
Thus, the changeover member can be constructed with a simple structure without increasing the number of parts.
Furthermore, the change over member can include an engagement portion adapted to be brought into engagement with the operating portion.
Thus, the locking body can be held in the release position in a more ensured fashion by bringing the operating portion into engagement with the engagement portion.
Furthermore, the passage holes may be formed in a holding member mounted on a core of the steering wheel, and the locking body may be mounted on the holding member in such a manner as to be moved thereon between the lock position where the locking body is brought into engagement with the plurality of pins and the release position where the locking body is released from the engagement with the plurality of pins.
Thus, the plurality of passage holes and at least the part of the changeover member can easily be formed in the holding member formed of synthetic resin or the like. In addition, the locking body can easily be mounted on a core of the steering wheel via the holding member.
According to a second aspect of the invention, there is provided an air bag module mounting structure in which an air bag module is mounted on a steering wheel by allowing a plurality of pins provided on a bottom of the air bag module in such a manner as to protrude therefrom to pass through a plurality of passage holes formed in a steering wheel and bringing a hook portion formed in each of the plurality of pins into engagement with a locking body provided in the plurality of passage holes, the air bag module mounting structure being characterized in that the locking body is constituted by a single continuous resilient wire, and that the engagement of the locking body with the plurality of hook portions is released at one time by displacing the locking body to a release position.
Thus, according to the first aspect of the invention, the engagement between the hook portions and the locking body at the plurality of locking locations can be released at one time by displacing the locking body to the release position through a one-touch or single operation, whereby the air bag module can easily be removed from the steering wheel.
The locking body may be formed into substantially a ring-like shape which is partially opened there along and is constructed so as to be diametrically contracted or expanded against its own resiliency in conjunction with the movement thereof to the release position.
Thus, the engagement between the hook portions and the locking body at the plurality of locking locations can easily be released through diametrical contraction or expansion of the locking body at the release position.
In addition, recess portions may be formed on the locking body for releasing the engagement of the locking body with the hook portions with the locking body being displaced to the release position.
Thus, the recess portions of the locking body are allowed to confront the hook portions through a small displacement of the locking wire to the release position, whereby the engagement between the hook portions and the locking body can easily be released.
In addition, an operating portion may be provided on the locking body for displacing the locking body to the release position.
Thus, the locking body can easily be displaced to the release position through operation of the operating portion.
Further, holding portions may be provided on the steering wheel for holding the locking body at positions confronting said passage holes, respectively, and the locking body may be constructed to be separated away from the holding portions with the hook portions in the pins being in engagement with the locking body.
Thus, the locking body can be held in the mounted status where the locking body corresponds to the respective passage holes by the holding portions in an ensured fashion, and when the hook portions in the respective pins are brought into engagement with the locking body the locking body is separated away from the holding portions and is then brought into a press engagement with the hook portions by virtue of its own resiliency, whereby the air bag module can rigidly be locked and held onto the steering wheel.
Further, the pins and passage holes may be provided at least three, respectively.
Thus, the air bag module can be locked and held onto the steering wheel at three or more locking locations in a stable fashion.
Further, the passage holes may be formed in a holding member mounted on a core of the steering wheel, and the locking body may be mounted on the holding member in such a manner as to be moved between a lock position and the release position.
Thus, the plurality of passage holes can easily be formed in the holding member formed from a synthetic resin, and the locking body can simply be mounted on the holding member.
Still further, the locking body may be brought into engagement with the hook portions from inside of the respective pins and be diametrically contracted when the locking body is operated so as to be moved to the release position, whereby the engagement of the locking body with the respective hook portions is released.
Thus, when the locking body is operated so as to be moved to the lock position the locking body is diametrically contracted inwardly of the respective pins, whereby the engagement between the locking body and the respective hook portions can easily be released.
Furthermore, the locking body may be brought into engagement with the hook portions from outside of the respective pins and be diametrically expanded when the locking body is operated so as to be moved to the release position, whereby the engagement of the locking body with the respective hook portions is released.
Thus, when the locking body is operated so as to be moved to the lock position the locking body is diametrically expanded outwardly of the respective pins, whereby the engagement between the locking body and the respective hook portions can easily be released.
According to a third aspect of the invention, there is provided an air bag module mounting structure in which an air bag module is mounted on a steering wheel by allowing a plurality of pins provided on a bottom of the air bag module in such a manner as to protrude therefrom to pass through a plurality of passage holes formed in a steering wheel and bringing a hook portion formed in each of the plurality of pins into engagement with a locking body provided in the plurality of passage holes, the air bag module mounting structure being characterized in that the locking body is constituted by a single continuous wire which is formed into substantially a ring-like shape and that the engagement of the locking body with the plurality of hook portions is released at one time by rotating the locking body to a release position.
Thus, the engagement of the hook portions and the locking body at the plurality of locking locations can be released at one time by rotating the locking body to the release position through a one-touch or single operation, whereby the air bag module can easily be removed from the steering wheel.
In the an air bag module mounting structure, recess portions may be formed on the locking body for releasing the engagement of the locking body with the hook portions with the locking body being rotated to the release position.
Thus, the recess portions on the locking body are allowed to confront the hook portions by rotating the locking wire to the release position, whereby the engagement between the hook portions and the locking body can easily be released.
In addition, an operating portion may be provided on the locking body for rotating the locking body to the release
Thus, the locking body can easily be rotated to the release position by operating the operating portion.
In addition, holding portions may be provided on the steering wheel for holding the locking body at positions confronting the passage holes, respectively, and the locking body may be constructed to be separated away from the holding portions with the hook portions in the pins being in engagement with the locking body.
Thus, the locking body can be held in a mounted status in which the locking body is allowed to confront the respective passage holes by the holding portions in an ensured fashion. Then, when the hook portions in the respective pins are brought into engagement with the locking body the locking body is separated away from the holding portions and is then brought into a press engagement with the hook portions, whereby the air bag module can rigidly be locked and held onto the steering wheel.
Further, the pins and passage holes are provided at least three, respectively.
Thus, the air bag module can be locked and held stably onto the steering wheel at three or more locking locations.
The passage holes may be formed in a holding member mounted on a core of the steering wheel, and the locking body may be mounted on the holding member in such a manner as to be rotated between a lock position and said release position.
Thus, the plurality of passage holes can easily be formed in the holding member formed from a synthetic resin or the like and moreover, the locking body can simply be mounted on the holding member.
According to a fourth aspect of the invention, there is provided an air bag module mounting structure in which a plurality of pins provided on one of either a bottom or external side of an air bag module and an opposite side of a steering wheel main body which confronts either the bottom or external side of the air bag module in such a manner as to protrude there from are allowed to pass through a plurality of passage holes formed in the other of either said bottom or external side of said air bag module and the opposite side of the steering wheel main body, respectively, and in which a hook portion formed in each of the pins is brought into engagement with a locking body provided in such a manner as to extend over the passage holes, whereby the air bag module is mounted on a steering wheel, the air bag module mounting structure being characterized in that an operating portion is provided on the locking body for changing over the status of the locking body between a lockable status in which the air bag module can be locked onto the steering and a removable status in which the air bag module can be removed from the steering wheel, and that a guide member is provided on the air bag module or the steering wheel main body for guiding the displacement of the locking body between the lockable status and the removable status.
The air bag module or the steering wheel main body may includes plurality of passage holes and comprise a holding member for holding the locking body, and the guide member may be provided on the holding member.
Further, the guide member may be constituted by a projection or an elongate projection disposed in such a manner as to extend in directions in which the operating portion is operated.
Still further, the locking body may be constituted by a single continuous resilient wire, and the operating portion may be formed by bending the resilient wire into substantially a U-shape, and the projection or elongate projection may be disposed in such a manner as to extend between extreme ends of an operation area of the operating portion.
Furthermore, the locking body may be constituted by a single continuous resilient wire, wherein the operating portion may be formed by bending the resilient wire into substantially a T-shape, and wherein the projection or elongate projection may be disposed in such a manner as to extend along an upper bottom portion of the operating portion formed into substantially a T-shape.
According to the above structure, the engagement between the hook portions and the locking body at the plurality of locking locations is released at one time by only displacing the locking body from the lockable status to there movable status. Moreover, when the locking body is displaced, since the operating portion is guided by the guide member, the looseness of the operating portion is prevented, whereby the locking body can be displaced easily and smoothly. Thus, the air bag module can be mounted on and dismounted from the steering wheel easily and quickly.
Another object of the invention is to provide a steering wheel with an air bag device which facilitates the control of the stroke of a horn switch mechanism and which can reduce restrictions on the design of steering wheels of the type.
With a view to attaining the object, according to a fifth aspect of the invention, there is provided a steering wheel with an air bag device comprising a steering wheel main body, an air bag module having an air bag cover which can oscillate relative to the steering wheel main body and a horn switch mechanism adapted to activate a horn when a pair of contacts disposed spaced away from each other is brought into contact with each other through oscillation of the air bag cover, wherein the horn switch mechanism is provided integrally with the air bag module, and wherein the air bag module is constructed so as to be fixed to the steering main body via a snap-lock mechanism on a bottom or external the thereof.
According to the fifth aspect of the invention, the stroke of the horn switch mechanism can be controlled before the air bag module is assembled to the steering wheel main body by providing the horn switch mechanism integrally with the air bag module. In addition, when so controlling the stroke of the horn switch mechanism, since most of the air bag module is exposed to the outside, even if there are errors in producing and assembling constituent components, the stroke of the horn switch mechanism can easily be corrected to a set value. Additionally, the stationary portion of the air bag module relative to the steering wheel main body can be constructed not to oscillate. Due to this, the air bag module can be fixed to the steering wheel main body in a stable fashion.
In addition, the snap-lock mechanism may include a plurality of pin portions provided on one of a bottom of the air bag module and a confronting surface of the steering wheel main body which confronts the bottom of the air bag module in such a manner as to protrude therefrom, a plurality of passage holes formed in the other of the bottom of the air bag module and the confronting surface of the steering wheel main body which confronts the bottom of the air bag module and a locking body adapted to be brought into engagement with hook portions formed in the pin portions when the pin portions are allowed to pass through the passage holes, respectively.
The air bag module is fixed to the steering wheel main body by allowing the pin portions to pass through the passage holes while pushing back the locking body so that the hook portions of the pin portions are brought into engagement with the locking body, whereby not only can the air bag module be mounted on the steering wheel main body easily but also the air bag module can be fixed to the steering wheel main body in a stable fashion. Moreover, the snap-lock mechanism is constructed simply.
Additionally, the air bag module may include a stationary plate having the plurality of pin portions and a movable plate adapted to oscillate relative to the stationary plate and having the air bag cover mounted thereon, the stationary plate comprising side pieces disposed on both sides of a center line which bisects the steering wheel in a neutral state which are connected to each other.
When the pin portions on the stationary plate are allowed to pass through the passage holes in the steering wheel, both the side pieces are inclined and the pin portions are prevented from being inclined, whereby there occurs no case where the air bag module is supported unstably.
Further, at least part of the stationary plate may be brought into abutment with a stepped portion formed on the steering wheel main body.
Even if the driver of the vehicle strongly presses against the air bag module with the intention of activating the horn, the stationary plate is prevented from being deformed by the pressing force.
Moreover, the stationary plate may have a cross section which is formed into substantially a U-shape.
The strength of the stationary plate is improved, whereby the deformation of the stationary plate is prevented preferably.
Further, at least a pair of pin portion may be provided on each of the side pieces of the stationary plate, and at least three stepped portions may be provided on the steering wheel main body.
The stationary plate may be disposed stably relative to the steering wheel main body.
Still further, the horn switch mechanism may be provided on the stationary plate at a position which is closer to the air bag cover than to a pin support portion which supports the pin portions.
The horn switch mechanism is provided at a position in the vicinity of the height of the center of the gravity of the air bag module. This allows the air bag module to be displaced substantially uniformly as a whole even if the vehicle is suddenly turned or the steering wheel is drastically turned.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.